Antarctica’s ozone hole has opened to 26 million square kilometers this year, according to the latest measurement from the European Space Agency’s (ESA) Copernicus Sentinel 5P satellite. This exposed area of atmosphere is equivalent to three times the size of Brazil, making the current hole one of the largest ever seen. The announcement of its growth attracted worldwide attention.
The basics about the ozone layer and its hole
Ozone is a molecule made up of three oxygen atoms. Ozone in the stratosphere is formed when molecular oxygen (O2) transforms into a highly reactive particle that can effectively absorb ultraviolet (UV) radiation. Ultraviolet waves break down oxygen molecules and they recombine to form ozone molecules (O3). When the new gas receives enough radiation, it “breaks down” again into molecular oxygen (O2) and atomic oxygen (O), which soon becomes O3 again. Thanks to the cycle of ozone creation and destruction, the Earth has a natural shield against UVC radiation, the sun’s most harmful radiation. The existence of this layer is crucial to life as we know it.
Research into stratospheric ozone on Earth dates back to 1913. Decades later, scientists discovered the presence of artificial substances that can destroy the protective O3. Mexican scientist Mario Molina and American Sherry Rowland proposed in 1974 that chlorofluorocarbons (CFCs), chemical compounds used in industry, decompose in the stratosphere, releasing chlorine and bromine particles that destroy accumulated ozone. In 1985, researchers from the British Antarctic Survey confirmed the CFC theory and their reports led to them discovering a “hole” in the ozone layer in Antarctica.
Why is there an ozone hole in Antarctica?
The famous “hole” in the ozone layer in Antarctica is not a “hole,” but rather a drastic dilution of the O3 concentration in this region. As the thickness of the ozone layer decreases, so does its ability to block the sun’s ultraviolet radiation. The uncovered land areas are directly affected by UV radiation and have to contend with consequences such as melting ice and cases of skin cancer.
It is no coincidence that the strongest thinning occurs at the South Pole. Antarctica acts as a kind of natural cage for gases. The atmospheric conditions isolate its air mass from the rest of the planet while it absorbs a greater amount of particles from other latitudes. Ozone-depleting chlorofluorocarbons tend to concentrate at the pole and collect in ice-filled structures known as stratospheric clouds. The more CFCs are produced, the more ozone-depleting particles are trapped in clouds.
In 1987, two years after the hole was discovered, the Montreal Protocol was signed. Most countries have committed to drastically reducing the production of halocarbon gases. Since then, the recovery of the ozone layer has progressed gradually. Overall, climatologists predict a successful recovery, even if the path is full of ups and downs.
The hole in the ozone layer is driving and worsening Antarctica’s melting
Melting ice in Antarctica represents a rise in sea levels that directly impacts global climate, economic and social conditions.
Why was the loophole opened if CFCs are banned?
The ozone cycle is a complex and delicate process. The ozone layer itself fluctuates in density throughout the different seasons. Likewise, chlorofluorocarbons produced over decades remain in the Antarctic atmosphere. The stability of ozone depends on several factors, although notable geological or social events may affect its recovery.
The size of the hole also varies from year to year. In 2022 it reached 25 million kilometers, while in 2021 it reached its historic low. In general, the scientific community believes that the size is decreasing, which is a sign of a gradual recovery.